Abstract
Deoxygenation of fatty acid ethyl esters (FAEE), obtained by transesterification of vegetable oils with ethanol, is a viable route to produce hydrocarbons such as aromatics, light gases and alkenes in the range of renewable diesel and jet fuel. To find the thermodynamic limits of FAEE deoxygenation, a simulation was conducted in the software Aspen Plus V14, using Peng Robinson as thermodynamic model, and the Gibbs reactor to identify preferable products. Soybean oil was chosen as FAEE feedstock. The first condition tested was T = 300 °C, P = 1 bar and FAEE feed = 100 kg/h. Sensitivity analyses were conducted to evaluate the impact of reaction temperature and pressure in the product composition, and aromatics benzene and toluene, as well as CH4, CO and CO2 were the products obtained in thermodynamic equilibrium. Conversely, it is possible to interrupt the reaction before reaching the equilibrium, which could lead to the formation of alkenes, for further addition of aromatics if jet-fuel is a target. Therefore, to simulate this condition, the aromatic compounds were excluded from the components list, so that higher hydrocarbons could be prioritized. The results confirmed that linear and branched C15-C18 alkenes were preferentially formed, accompanied by CO and CH4. Therefore, the kinetic aspect of FAEE deoxygenation is very important to determine the reaction outcome, because hydrocarbons in the range of renewable diesel will be transformed to aromatics when the equilibrium is reached. This means that is possible to play with operating conditions to achieve either diesel or jet-fuel.
